| 摘要 |
A method of controlling the air-fuel ratio of a mixture being supplied to an internal combustion engine, in a feedback manner responsive to an output signal from an O2 sensor arranged in the engine exhaust system for sensing the concentration of a component in exhaust gases from the engine to produce as the output signal a normally fluctuating output signal indicative of the concentration. The air-fuel ratio is controlled to a desired value by means of at least one of proportional control applying a first correction value to correct the air-fuel ratio when the output signal changes from a rich side to a lean side or vice versa with respect to a predetermined reference value, and integral control applying a second correction value to correct the air-fuel ratio whenever a predetermined period of time elapses so long as the output signal remains on the lean side or on the rich side with respect to the predetermined reference value. A correcting amount is determined in response to the rate of change in the output signal of the O2 sensor. The second correction value is to be increased or decreased by means of the correcting amount, depending upon whether the output signal remaining on the lean side or on the rich side.
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